Hydrostatic holding devices have now been used for a number of years to hold work parts for machining operations. These devices generally utilize a flexible wall that can be expanded by hydraulic pressure to make proper contact with a wall of a part. An early U.S. patent in this field, issued May 8, 1956, to George L. Atherholt, Sr. et al, No. 2,744,756, disclosed the expansion of a thin wall steel cylinder by hydrostatic pressure to grip a work part. A further more recent advance in this art came with the issuance of U.S. Pat. No. 4,116,453 (Sept. 26, 1978) to Eugene R. Andre. This patent teaches that a thin-wall cylindrical part, which might be subject to distortion by outside wall pressure, can be tightly gripped with a pliant sleeve which is urged against the part by pressure on the pliant sleeve on the side opposite the work part.
The present invention has an object to provide a hydrostatic holding device which is not limited to circular or cylindrical parts but which may function to hold irregularly shaped parts or flat parts in a manner to permit machining without vibration or distortion.
A further object of the invention is the provision of a holding device which is readily adaptable to different shapes and sizes of parts.
Other objects and features of the invention will be apparent in the following specification and claims in which the invention is described with details directed to persons skilled in the art on the manner and process of using the invention all in connection with the best mode contemplated for the practice of the invention.